This wiki page provides a list of resources within the NEEShub related to hybrid simulation (HS) and real-time hybrid simulation (RTHS) for earthquake engineering. These technologies are enabling researchers to conduct a wide array of experiments to examine the behavior of structures under realistic conditions.

'''HYBRID SIMULATION (HS)'''

Hybrid simulation is a cost-effective experimental technique to evaluate the dynamic performance of large civil structures. In hybrid simulation, a civil structure is partitioned into two substructures, (1) physical substructure, which usually includes more complex components and (2) numerical substructure, which usually includes well-studied components. And the coupling between the two substructures is achieved by enforcing equilibrium and compatibility at the interface.

'''REAL-TIME HYBRID SIMULATION (RTHS)'''

Advances in embedded systems with hard real-time computing capabilities have facilitated the use of real-time hybrid simulation methods. Real-time hybrid simulation, which is performing hybrid simulation at real time, offers the capability of preserving rate dependence while examining the global performance (the reference structure) and local performance (the physical substructure). In RTHS, the interface interaction between the substructures is enforced by servo-hydraulic actuators or shake table which act as a transfer system. The transfer system should be designed and controlled to ensure that all the interface boundary conditions are satisfied at real time. It is known that the stability and performance of RTHS are functions of three major factors, (1) the overall dynamics of a reference system, (2) how a reference system is partitioned into numerical and physical substructures, and (3) how well the interface boundary conditions are met by a transfer system.

A typical RTHS system usually consists of the cyber and physical components,

'''Cyber Components:'''
Those components that execute user programmed digital components (numerical model and actuator motion control scheme) and subsequently communicate with the sensing and analog control system through I/O modulus. Real-time kernel is included to meet the time scale constrains of RTHS. Cyber components usually include,

• Transfer System Control: Digital controller is usually included to further enhance the synchronization between computational and experimental substructures.

• Visualization and Control Dashboard: User interfaces can be included to facilitate test operation and visualize results during the tests.

'''Physical components:'''
Physical components usually include,

• Physical Substructure: It includes more complex components of the reference structure which will be constructed in the lab.

• Sensing System: In HS and RTHS, different sensors, e.g. accelerometers, LVDTs, force transducers, etc., are used to measure the restoring force of the physical substructure and monitor the performance.

• Transfer System: The interface interaction between the substructures is enforced by servo-hydraulic actuators or shake table which act as a transfer system.